Exhaust gas emitted from an internal combustion engine, particularly a diesel engine, is a heterogeneous mixture that contains gaseous emissions such as, but not limited to, carbon monoxide (“CO”), unburned hydrocarbons (“HC”) and oxides of nitrogen (“NOx”) as well as condensed phase materials (liquids and solids) that constitute diesel particulate matter (“PM”). Catalyst compositions, typically disposed on catalyst supports or substrates, are provided in an engine exhaust system as part of an aftertreatment system to convert certain, or all of these exhaust constituents into non-regulated exhaust gas components.
One type of exhaust treatment technology for reducing emissions is a diesel particulate filter (“DPF”). The DPF is designed to remove diesel particulate matter or soot from exhaust gas of a diesel engine. The diesel particulate matter removed from the exhaust is entrapped by, and entrained in, the DPF. When accumulated soot reaches a predetermined level the DPF is either replaced or regenerated. Replacement or regeneration ensures that soot removal continues at desired parameters.
Many engines include a controller having a soot out model that predicts soot accumulation in the DPF. The soot out monitor employs various engine operating parameters to predict soot accumulation levels in the DPF. The operating parameters include duration and number of accelerations, duration of operating at constant RPM above idle, and idle time. Inaccurate soot accumulation predictions could lead to premature replacement or cleaning of a DPF, or operating conditions in which soot is not removed at desired levels. Accordingly, it is desirable to provide a soot out model that more accurately reflects soot accumulation during all operating conditions.